Problem writing in sd card (Arduino Mega)

I’m using Arduino Mega 2560, with a sd shield.
I’m trying to learn how to write data on the sd, so i’m using this example program:

/*
  SD card read/write
 
 This example shows how to read and write data to and from an SD card file 	
 The circuit:
 * SD card attached to SPI bus as follows:
 ** MOSI - pin 11
 ** MISO - pin 12
 ** CLK - pin 13
 ** CS - pin 4
 
 created   Nov 2010
 by David A. Mellis
 modified 9 Apr 2012
 by Tom Igoe
 
 This example code is in the public domain.
 	 
 */
 
#include <SD.h>

File myFile;

void setup()
{
 // Open serial communications and wait for port to open:
  Serial.begin(9600);
   while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }


  Serial.print("Initializing SD card...");
  // On the Ethernet Shield, CS is pin 4. It's set as an output by default.
  // Note that even if it's not used as the CS pin, the hardware SS pin 
  // (10 on most Arduino boards, 53 on the Mega) must be left as an output 
  // or the SD library functions will not work. 
   pinMode(10, OUTPUT);
   
  if (!SD.begin(4)) {
    Serial.println("initialization failed!");
    return;
  }
  Serial.println("initialization done.");
  
  // open the file. note that only one file can be open at a time,
  // so you have to close this one before opening another.
  myFile = SD.open("test.txt", FILE_WRITE);
  
  // if the file opened okay, write to it:
  if (myFile) {
    Serial.print("Writing to test.txt...");
    myFile.println("testing 1, 2, 3.");
	// close the file:
    myFile.close();
    Serial.println("done.");
  } else {
    // if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
  
  // re-open the file for reading:
  myFile = SD.open("test.txt");
  if (myFile) {
    Serial.println("test.txt:");
    
    // read from the file until there's nothing else in it:
    while (myFile.available()) {
    	Serial.write(myFile.read());
    }
    // close the file:
    myFile.close();
  } else {
  	// if the file didn't open, print an error:
    Serial.println("error opening test.txt");
  }
}

void loop()
{
	// nothing happens after setup
}

When I run the sketch, it always says “initialization failed!”
I dont know which is the problem, i’ve tried to set the jumper in all the four positions, but it still dont work.
Have someone any ideas?
Here some photos of how everything is connected.





Thanks.

You have

pinMode(10, OUTPUT);

it should be pin 53, but I don’t know if that fixes your problem. Is the card formatted? The jumper is probably for selecting the CS pin. Return it to the original position, then find out what it does. If it does what I think it does, resolve never to alter it.